Suggestion: M593 Input Shaping Calibration Tower Slicer G-Code

When using the ringing_tower.stl method to calibrate Input Shaping, the following code is recommended: `M593 F{(layer_num < 2 ? 0 : 15 + 45.0 * (layer_num - 2) / 297)} ; Hz Input Shaping Test` While this does work, it causes the Input Shaping value to change over the entire model with a set value only showing up on a single line. Picking the "best' layer is very difficult. I instead used this: ``` {if (layer_num - 2) % 25 == 0} ; Layer {layer_num} ({layer_z}mm) M593 F{30 + 2 * (layer_num - 2) / 25} {endif} ``` This sets the value for the entire tier instead, giving ~5mm of model to analyze and compare against the other layers. In my case I found values below 30 were just, well bad, so I started at 30 and went up to 52 in intervals of 2. Once I got a range that looked "best" then I could print the model again with better refinement. This was done with an if instead of inline in order to allow multiple settings - for instance different ranges for the X and Y.